1. Field of the Inventive Concept
The present inventive concept relates to a nonvolatile memory device using a variable resistive element.
2. Description of the Related Art
In general, examples of a nonvolatile memory device that uses a resistance material include a resistive Random Access Memory (RRAM), a phase change RAM (PRAM), a magnetic RAM (MRAM), and the like. While a dynamic RAM (DRAM) or a flash memory stores data using an electric charge, a nonvolatile memory device that uses a resistance material stores data using a change in resistance of a variable resistive material (RRAM), a change in state of a phase change material (PRAM), such as a chalcogenide alloy, and a change in resistance of a magnetic tunnel junction (MTJ) thin film due to a magnetization state of a ferromagnetic substance (MRAM).
In a phase-change memory cell, for example, when a phase change material is heated and then cooled, its state rapidly changes into a crystalline state or an amorphous state. The phase change material in the crystalline state has low resistance and phase change material in the amorphous state has high resistance. Thus, the crystalline state is referred to as a set state and stores a data “0” defined as set data, while the amorphous state is referred to as a reset state and stores a data “1” defined as reset data or data.
Meanwhile, in an input/output (IO) repair scheme of a phase change memory device, a failed memory column is replaced by a redundancy memory column. A phase change memory device may simultaneously repair at least one failed memory column with at least one redundancy memory column according to the IO repair mode. For example, when the IO repair mode is a ×1 mode, memory columns are repaired in units of one column. When the IO repair mode is a ×2 mode, memory columns are repaired in units of two columns.
In addition, a first circuit block of writing data in a phase change memory cell may be arranged to be spaced apart from a second circuit block of reading data from a phase change memory cell. That is to say, the first circuit block and the second circuit block may not be adjacent to each other. For example, the first circuit block may be disposed at one side of a memory cell array and the second circuit block may be disposed at the other side of the memory cell array.
When a write operation or a read operation is performed on a particular memory cell, it is necessary to know whether the particular memory cell has failed or not. That is to say, repair information should be provided to the first circuit block and the second circuit block. In order to provide repair information to the first circuit block and the second circuit block spaced apart from each other, a layout, such as an array of wires, of a memory cell array may become complicated, or a block area for repairing may become larger. That is to say, the repairing of failed memory cells may not be efficiently performed.